Liquid fuel heater



June 21, 1960 D. M. FOLEY LIQUID FUEL HEATER Filed Nov. 7. 1955 l I l *ll l INVENTOR.

BY Wyw;

UnitedStates Patent O LIQUID FUEL HEATER Daniel Murray Foley, New York,N .Y., assignorto West Coast Steel Products Co., Riverside, Calif., acorporatiouof California Filed Nov. 7, 1955, Ser. No. 545,407

3 Claims. (Cl. 15S-91) liquidA fuel, suchas fuel oil. Qn the top of thisreceptacle there is a cover in which there is an opening through whichthe receptacle can be refilled and through which'ia torch may beinserted for the purpose of igniting the fuel oil in starting theheater. This opening is normally covered by an adjustable air regulatorwhich permits air .to enter the receptacle and to mix with vaporsgenerated from the surface of the fuel oil. The usual cover has anupstandng collar which has now been more or less standardized to have a6 diameter. On this collar there is positioned an upstanding stack. Thestack frequently is made up of two or even more sections of sheet metalwhich telescopically fit together. The lower of these sections usuallyhas air inlet openings formed in the walls thereof throughwhich'additional air may enter the stack to complete combustion. This lowersection frequently f has the air inlet `openings in the form ofdownwardly directed louvers and consequently, it is frequently re'-erredto as the louvered `section of the stack. It consti- `tutesthevcombustion chamber of the heater inasmuch as most of the intenseburningof the fuel takes place therein. This is highly desirable in thatthe walls of the louvered section become quite hot and tend to radiate4the -heat laterally, it being desirable that a direct ascent of the hotgases and products of combustion be minimized.

It has heretofore been recognized in heaters of this character that itis highly desirable to return to the covered fuelreceptacle a portion ofthe heated products of '2,941,586 Patented June 21, 1960 ICC4 relativelyexpensive to manufacture. Also, the presence of the auxiliary stack orstacks at the sides of the main stack is such as to frequently interferewith the positioning of the heater beneath a tree which is to be heatedand kept from freezing during cold weather.

A primary object of the present invention is to provide an improvedliquid fuel heater wherein a portion of the products of combustion and/or air are returned to the liquid fuel receptacle so vas to gain theadvantages of more complete combustion elimination of smoke andelimination of soot deposits. However, instead of adding an auxiliarystack to the exterior of the main stack I have found that if a tube ispositioned in the main stack which has proper dimensions or proportionswith respect to the main stack, the desirable return or rte-circulationof a portion ofthe gases in the stackwill be self-induced through thetube. Consequently, it is possible for me to gain all of the advantagesof more complete combustion and at the same time reduce expense ofmanufacture and the objection of having an auxiliary stack at the sideof the main stack which interferes with the positioning of the heaterbeneath a tree.

With the foregoing and other objects in view, which will be mademanifest in the following detailed description and specifically pointedout in the appended claims, reference is had to the accompanyingdrawings for an illustrative embodiment of the invention, wherein:

Figure 1 is a top plan view of a heater embodying the present invention;and

Pig. 2 is a sectional view taken substantially upon the line 2-2 uponFig. l.

combustion and/ or some of the air that is admitted tothe staclcthroughthe louver openings.` The advantages of "returning or re-circulatingsome of the products of cornbustion and/ or air admitted to the stackhave been recognized in VUnited States Letters Patent No. 2,284,157,issued May 26, 194,2,` to Arthur Stephen Leonard. When a portion of theproducts of combustion and/or air admitted to the stack are returned tothe fuel receptacle, a

frnore complete combustion seems to result in that heater Vinthe mainstack. A portionY of the gases rising in the main stack, whether they beair or products of combustion, or a mixture of both, encounter thedownwardly -directed entrance `to the auxiliary stack and on. passingtherethrough are returned by the auxiliarystack to the Afuel receptacle.

An objection to that form` of construction which is disclosed in theLeonard patent is that the construction is Referring to the accompanyingdrawings wherein similar reference characters designate similar partsthroughout, the improved heater employs for purposes of convenience,expense, and simplicity of manufacture, a fuel receptacle 10 vthat maybe conventional. This fuel receptacle is designed to receive and hold anadequate supply of liquid fuel, such as fuel oil 11. It is equipped witha cover 12 and in conformity with conventional practice this cover hasan upstanding, centrally located, collar 13. The diameter of'such collarhas been more or less standardized by manufacturers of heaters of thistype `to have a 6" diameter. `In the cover there is an opening M throughwhich air may be admitted to the receptacle 1.0.V

The size of this'opening can be adjusted or varied by a rotatable`damper 15. The extentto which the opening is opened and the extent towhich air is admitted tol the fuel receptacle lil governs to a largeextent the rate of burning and the magnitude of the iiame. Y t Y On thecollar 13 there is positioned an npstanding stack and this stack isusually formed of twolsections, the lower section being-indicated at 16and th'e upper section at 17. These` two sections telescopically iittogether and the lower section telescopes over the collar 13. The lowersection 16 forms the combustion chamber of the heater and is commonlyreferred to as the louvered sectionin that downwardly directed louvers18 are formed in its walls. These louvers are formed by horizontallyslitting the sheet metal from which the lower section i6 is formed anddepressing inwardly the metal below the'slit as indicated at 19. Thatportion of the metal which is immediately above theslit is pressedoutwardly as indicated at 19 so thatthere are air openings formed in thewalls of the louvered section for the ingress of air. As indicated onFig. l, I prefer to ha've ten vertical rows of louvers in a louveredsection whose diameter at the collar 13 is approximately 6, and whosediameter at the top is approximately 8". These louvers are arranged incircumferential rows, the lowermost row being located approximately35/16 above the bottom of the louvered section. The uppermost row ispreferably .located-12%" above the bottom of the louvered section. i

9 utransparent material.

3 The upper portion '17 ofthe stack 'is generally imperforate and iscylindrical and its height seems to have no important bearing upon .thepresent invention.

Within the louvered section there is disposed a central t tube 20preferably formed of seamless steel tubing having a Wall Vthicltness'ofVl/s". Adjacent the top of 'this section of tubing steel straps 21 arewelded to opposite sides thereof. Near the bottom ofthe tubing 20 asimilar pair of straps 22 are welded toopposite sides thereof. Thesestraps provide outwardly extending arms of upper and lower spiders, thelengths of which are such that they will engage the interior ofthelouvered section between the louvers and support the .tubing thereinwith the top of the tubing v20 disposed atv an elevation that ispreferably even with the rstrow-of lonvers beneath the top row oflouvers. At all events the tcp of the tubing Zt? isY disposed below thetop row of' louvers. The bottom of the tubing 20 extends down into thereceptacle 10 a short distance. That is, itV extends below the collar 13on the cover and below the. bottom edge of the louvered section.

I am aware that liquid fuel heaters of this general character haveAheretofore been provided wherein an 'openended tube is supported withinthe lower portion of the stack. However, in order to develop orself-induce a downward liow of air and/or products of combustion throughthe tube 20 .in order to gain the advantages of re-circulation, therelative proportions :of the tubing with relation to the louveredsection are somewhat critical. ln the preferred embodiment of myinvention the length of the tubing 20 is 12". and has an outsidediameter of 2." with al wall thickness. It extends below the ,bottom ofthe collar 13 a distance of 11/2". In effect, there fore, the diameterof the tubing 2G is approximately one'- third of the diameter of thecollar 13 vand the bottom of the louvered section. Also, the distancethat the bottom of the tubing extends below the bottom of the collar 13is approximatelyV three-fourths of the diameter of the tubing. Thelength of the tubing may be regarded as being roughly six times itsdiameter with the tubing extending downwardly beneath the collar on the.cover slightly less than a diameter.

' When the tubing and louvered: section have these relative proportionsandthe position of the tubing in the louvered section is as vabovedescribed, it will be found ythat a relatively strongldown-draft isself-induced in the vtubing returningto the fuel receptacle 10. productsof combustion. and/ or air-thatis; admitted through. the uppermostlouver openings. This down-draft. is readily observable ifl the uppersection 17 of the stack is made of Also, if a lighted wick is loweredVthroughthe upper section 17 to Va location immediately above the top ofthe tubing 20 the time from the wick Y will bfe observed tovbe drawndownwardly into the tubing. f

1; Exactly why these .relative proportions of tubing and louveredsection Vwill..induce this. down-draftvand recirculation through thetubingI am unprepared testate.

,It is obvious, however, that for such adown-draft to 12 i als existthat pressure "over the'top of the tubing 20 must `the tubing 2.0 andthe walls of the louvered section between the louver openings. The llameappears .to be generally circular with indentations therein opposite theVlouver openings. The walls of the louvered section become quite hot andradiate heat laterally. The ascending products of combustion whichascend through the stack 17 are relativelyY cool and are readilyobservable tofbe free from smoke. ln fact, withthe opening 14 givenV anadjustment providing for a desired rateY of burning, if the. tubing 20and its, spiders vare .removed from the stack, the heater willimmediately begin to smoke noticeably.

Experiments have been conducted to ascertain what variation from theabove given preferred dimensions as it is obvious that if the tubing 20is made relatively short and of large diameter as compared with thediameter of the collar 13 that no .downward flow through the tubing willtake place, On the contrary the flame Vwithin the receptacle iti willrise inside of the tubing as well as on the outside. On the other`handif the tubing 20 is made very long and of very small diameter there willbe no downward ow therethrough, or even if such ow does exist, itseffect inproducing smokeless and sootless heater will be negligible.

Experiments that have been conducted as to possible variations are asfollows:

TEST #1.

Tube Dimensions Other Facts Diameter,

Length, inchesv inches Comments: Fire burns up center of tube, inclinedto choke, dleult, to light--very dirty-uncombusted gases are. notreturned Comments: Return action ls present---retnrnl action not asstrongcs. 12"

length x 2" diameter TEST #4 Comments: Length is ideal-diameter'allowsslight return action 1% is; as small as you may go on diameter VTEST #EY1% below bottomofstack.

Comments: ',Return action is present-not as strong as with 2" diameter"TEST #e 14 2 {ifg Wan' elowbottom of stack.

Comments: Return action is slight and only noticeable when regulator isY' wide open-no returnl action present under normal adjustment. Tube 1stoo long-top of tube is above top louver TEST #7 Y 1%" below bottomolstack:

Comments: No return action present-tube is too long TEST #8 y Yl/6"wal1. f l 15% 254e Tube flush; with bottom-ol' stack.

Comments: Return action 1s strongest As a conclusion from the results ofthese and other tests it is apparent that the length, diameter, andposition of -tne tubing in the louvered section is somewhat critical. lnorder to obtain the desired down-flow through the tubing, in a louveredsection fitting on a 6 collar 13 the diameter of the tubing should bebetween 1%" and 3%. The length of the tubing should be between 10i/2"and 131/2. The tube must project downwardly below the collar 13 aminimum of 1" and not more than 2". The top of the tubing must be belowthe top of the top louver openings. Some downward ow through the tubingtakes place if Ithe top of the tubing is slightly below the top of thetop louver openings but the downward ow through the tubing is best whenthe top of the tubing 20 is approximately even with the row of louveropenings next below.

It will be appreciated from the above described construction that themanufacture and installation of the tubing 20, together with itsspider-forming arms is relatively simple and inexpensive. The tubing maybe installed in a conventional heater very easily and at minimumexpense. It is not essential that the louvered section have a 6 diameterat its bottom and an 8" diameter at its top. If the louvered section yistapered in the opposite direction and has a shape somewhat similar tothat illustrated in Figs. 1 and 2 of the Leonard patent above referredto, similar results are obtainable as long as the tubing hasapproximately the same relative proportions with respect to the collar13, projects downwardly into the fuel receptacle below the collar from 1to 2 and terminates at its top below the uppermost louver opening.

Various changes may be made in the details of construction withoutdeparting from the spirit and scope of the invention as deiined by theappended claims.

I claim:

1. A heater comprising a covered liquid fuel receptacle having an airinlet in the cover and a stack extending upwardly from the cover, saidstack having air inlets in the walls thereof and a central tubesupported therein, the top of which terminates below the uppermost airinlet openings in the walls of the stack, the bottom of the tubeextending downwardly below the cover a distance approximately equal tothree-fourths of the diameter of the tube, the internal diameter of thetube being approximately one-third of the diameter of the stack at itsjuncture with the cover whereby down-flow of gases through the tube isinduced.

2. A heater comprising a covered liquid fuel receptacle having an airinlet in the cover and a stack extending upwardly from the cover, saidstack having air inlets in the walls thereof, the top of whichterminates below the uppermost air inlet openings inthe walls of thestack, the relative sizes of the parts being in approximately thefollowing proportions:

Diameter of stack at juncture with the cover-6",

Air openings in wall of stack disposed between 3%6" and 121/2" measuredvertically from juncture of stack with cover,

Diameter of tube 1% to 3%",

Length of tube lOl/2" to 13%", v

Distance to which bottom of tube extends below cover-1 to 2".

3. A heater comprising a covered liquid fuel receptacle having an airinlet in the cover and a stack extending upwardly from the cover, saidstack having air inlets in trie Walls thereof and a central tubesupported therein, the top of which terminates below the uppermost airinlet openings in the walls of the stack, the relative sizes of theparts being in approximately the following proportions:

Diameter of stack at juncture with cover-6",

Air openings in wall of stack disposed between 3%5 and 121/2 measuredvertically from cover,

Diameter of tube-2",

Lenth of tube-12",

Distance to which bottom of tube extends below cover-11/z".

References Cited in the le of this patent UNITED STATES PATENTS 877,871Snitjer Jan. 28, 1908 2,132,021 Forster Oct. 4, 1938 2,517,399 McCollumAug. 1, 1950 FOREIGN PATENTS 697,100 France Oct. 21, 1930

